It is noted that the phrase “printing device” as used in this document will be understood to include any device that provides a printing function. Thus the phrase “printing device” may, for example, refer to a multi-function device that includes a printing function as well as additional functions. Such additional functions may include, without limitation, one or more of the following: faxing, copying, scanning and the like. The phrase “laser printing device”, as used in this document, refers to any printing device that may employ an electrophotographic process to perform a printing function.
The electrophotographic process typically involves irradiating a photoconductor so as to form an electrostatic latent image on the photoconductor. Toner may then be transferred, by use of a developer apparatus, to the photoconductor so as to develop the latent image.
Once the latent image is developed, it may then be transferred to a media. In some laser printing devices, the latent image is directly transferred from the photoconductor to the print media. In others, the transfer of the latent image to the print media is via an intermediate transfer mechanism (e.g., an intermediate transfer belt).
Problems may occur if an improper amount of toner is presented to the photoconductor during latent image development. Presenting an excessive amount of toner to the photoconductor, for example, may over develop some areas of the latent image and thereby cause print quality defects. Additionally, some of the excess toner may become airborne and deposit, in an uncontrolled manner, onto various surfaces within the printing device. Airborne toner particles, for example, that deposit onto unintended areas of the photoconductor may negatively impact print quality. Airborne toner particles that deposit onto electrical or optical elements of a laser printing device may also negatively impact print quality as well as device reliability.
In addition, presenting an excessive amount of toner to the photoconductor can also be associated with charging the toner and agitating a toner supply more than what is necessary. This can accelerate the degradation of the toner properties and cause what is sometimes referred to as “toner wear”. Toner wear can negatively impact both print quality and device reliability.